Florida Department of CorrectionsJulie L. Jones, Secretary

Data and Methods: Release Cohort

Recidivism rates are calculated based on a release cohort—for this study, a group of prison inmates—released during a specified time period. The release cohort used to measure recidivism rates may vary. For example, a recidivism rate may be calculated for inmates released during a fiscal year or for all inmates released since a certain date. Because recidivism rates of state prison inmates do not vary much by year of release, this report relies on the latter method, calculating recidivism rates for inmates released from Department of Corrections custody from July 1995 through June 2001.

Data was collected on 106,167 prison releases involving 96,415 inmates during the six year study period. This number of releases is lower than those reported elsewhere by the Department, mainly because some inmates are released more than once on the same prison commitment. For example, an inmate who leaves prison on conditional release—a form of post-release supervision—can return to prison for a violation of supervision conditions (other than committing a new offense) and later leave prison again. For recidivism analysis, only the first such release is counted. Counting more than one of these releases would artificially lower the recidivism rates. This is because an inmate released twice who only recidivated after the second release would be counted both as a success (non-recidivist) and a failure.

Of these 106,167 releases, 2,643 (2.8%) were excluded from the analysis because they involved death, release out of state or to another prison system, escape, or a vacated (court-removed) sentence. Including these releases would also improperly lower the recidivism rates. Inmates released due to death cannot recidivate, and those released out of state are unlikely to recidivate in Florida. Releases to other prison systems must also be excluded because the true follow-up time can not be measured since the Department has no data on when the inmate was subsequently released. Those released by court-vacated sentences and the few who escape are excluded because they are unusual releases.

This analysis retained 85.7% of the 103,524 remaining releases (94,272 inmates), including 88,678 releases (81,737 inmates) with no missing data on important inmate characteristics relevant to recidivism. Almost all cases excluded for missing data have no score on the Test for Adult Basic Education because they did not take the test. Excluding these cases does not lower recidivism rate estimates in this study because the excluded cases have rates somewhat lower than those retained.

The study analyzed 80,919 releases of 74,467 male inmates and 7,759 releases of 7,270 female inmates. This study analyzes male and female releases separately, due to differences in their fundamental recidivism rates and because factors that influence recidivism affect males and females differently. Table 1 shows the final male and female cohorts broken down by the number of releases during each fiscal year (July - June) in the study period.

Table 2 describes the male and female release cohorts analyzed for this report. The characteristics presented are those found to predict recidivism rates best when used simultaneously. These characteristics were selected from 35 variables (counted in parentheses below) that cover 17 aspects of inmate characteristics in four general areas:

Where possible, multiple ways of measuring each variable were tested. These measures are those that met three qualifications:

correlated most with recidivism among multiple measures for each variable,

correlated least with measures used for other variables, and

survived appropriately in tests of a variety of statistical models of recidivism.

This study only analyzed characteristics for which the Department has data at the time an inmate is released from prison. This data is reliable, readily available, and should remain so over time. Data is either unavailable or inadequate to analyze post-release factors such as employment, drug and alcohol use, and housing stability, etc., which may also affect recidivism rates according to other research.

For more information about how these cohort characteristics were measured and selected, see the Technical Appendix.

Table 2. Characteristics of Inmate Releases

FACTOR

CATEGORY

MALES

FEMALES

N

%

N

%

Gender

80,919

91.3*

7,759

8.7*

Age at Release

UNDER 18

347

0.4

22

0.3

18 TO 24

20,046

24.8

930

12.0

25 TO 34

29,954

37.0

3,240

41.8

35 TO 49

27,334

33.8

3,336

43.0

50 TO 59

2,620

3.2

193

2.5

60+

618

0.8

38

0.5

Mean / Std. Dev.

32.1 / 9.2

33.9 / 7.9

Max / Min

91 / 15

79 / 15

BLACK

47,343

58.5

4,449

57.3

HISPANIC

4,469

5.5

240

3.1

Supervision - Any After Release

29,982

37.1

1,998

25.8

Months in Prison

1-12

20,323

25.1

3,005

38.7

13-24

24,134

29.8

2,606

33.6

25-36

13,965

17.3

1,100

14.2

37-48

8,319

10.3

490

6.3

49-60

4,837

6.0

244

3.1

61+

9,341

11.5

314

4.0

Mean / Std. Dev.

30.4 / 26.6

21.2 / 18.9

Max / Min

370 / 1

305 / 1

Disciplinary Reports - Total

0

36,396

45.0

4,302

55.4

1

13,491

16.7

1,294

16.7

2

7,218

8.9

586

7.6

3-6

12,059

14.9

861

11.1

7+

11,755

14.5

716

9.2

Mean / Std. Dev.

3.2 / 6.9

2.3 / 6.4

Max / Min

208 / 0

113 / 0

Custody Level at Release

COMMUNITY

2,650

3.3

337

4.3

MINIMUM

38,102

47.1

5,423

69.9

MEDIUM

26,719

33.0

1,705

22.0

CLOSE

13,448

16.6

294

3.8

Test for Adult Basic Education Grade Level - last before release

1-3.9

14,438

17.8

1,356

17.5

4-8.9

42,364

52.4

4,406

56.8

9-11.9

13,684

16.9

1,135

14.6

12-12.9

10,433

12.9

862

11.1

Mean / Std. Dev.

7.3 / 3.2

7.1 / 3.1

Max / Min

12.9 / 1

12.9 / 1

Prior Recidivism Events

0

41,631

51.4

4,606

59.4

1

17,291

21.4

1,599

20.6

2

10,459

12.9

856

11.0

3

6,228

7.7

444

5.7

4

3,176

3.9

171

2.2

5+

2,134

2.6

83

1.1

Mean / Std. Dev.

1.0 / 1.4

0.7 / 1.1

Max / Min

11 / 0

7 / 0

Most Serious Offense Type- Career

HOMICIDE

3,935

4.9

349

4.5

SEX/LEWDNESS

6,216

7.7

74

1.0

ROBBERY

17,227

21.3

906

11.7

OTHER VIOLENT

20,265

25.0

2,081

26.8

BURGLARY

17,322

21.4

882

11.4

PROPERTY

7,043

8.7

1,882

24.3

DRUGS

8,059

10.0

1,513

19.5

WEAPONS

338

0.4

17

0.2

OTHER

514

0.6

55

0.7

Property Offenses - Total

0

39,925

49.3

3,727

48.0

1

14,004

17.3

1,138

14.7

2

9,303

11.5

782

10.1

3+

17,687

21.9

2,112

27.2

Mean / Std. Dev.

1.7 / 3.0

2.4 / 5.2

Max / Min

111 / 0

120 / 0

Drug Offenses - Total

0

41,163

50.9

3,103

40.0

1

11,686

14.4

1,085

14.0

2

8,822

10.9

954

12.3

3+

19,248

23.8

2,617

33.7

Mean / Std. Dev.

1.6 / 2.5

2.2 / 2.9

Max / Min

35 / 0

41 / 0

Weapons Offenses - Total

0

69,543

85.9

7,304

94.1

1

7,879

9.7

359

4.6

2+

3,497

4.3

96

1.2

Mean / Std. Dev.

0.2 / 0.6

0.1 / 0.3

Max / Min

8 / 0

4 / 0

These characteristics of the release cohorts are factors that influence recidivism rates: either raising or lowering an inmate's risk of recidivism. For information about these factors, see Statistical Analysis; and for how they affect recidivism rates, see Factors Affecting Rates.